This project is designed to investigate changes in observer perception of lung tumors under controlled changes in image quality. Studies include measurement of the effect of viewing distance and image blurring on lung tumor perception. Image blurring is achieved through the introduction of transparent spacers between the original and duplicate process. LSF and MTF measurements are made on both the original and blurred images. Data will be analyzed using ROC Curves. Changes in image perception with changes in eye glass connection will also be measured.